Homo sapiens Exome Sequencing Data - CTLA4 Study 1. Homo sapiens

Using whole exome sequencing, we identified germline heterozygous mutations in CTLA4 in members of four families with severe immune dysregulation. Human CTLA4 haploinsufficiency caused dysregulation of FoxP3+ regulatory T (Treg) cells and lymphocytic infiltration of target organs, mimicking Ctla4 homozygous mice. Patients also exhibited a B cell phenotype, with progressive loss of B cells and accumulation of autoreactive CD21lo B cells. This study demonstrates a critical quantitative role for CTLA-4 in human immune homeostasis.